Date: Tue, 11 Mar 2008 09:35:37 -0400
From: Bill Moran <wmoran@collaborativefusion.com>
To: "Robins Tharakan" <tharakan@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: count * performance issue
Message-Id: <20080311093537.a60e2e3d.wmoran@collaborativefusion.com>
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In response to "Robins Tharakan" <tharakan@gmail.com>:

> Hi,
> 
> I have been reading this conversation for a few days now and I just wanted
> to ask this. From the release notes, one of the new additions in 8.3 is
> (Allow col IS NULL to use an index (Teodor)).
> 
> Sorry, if I am missing something here, but shouldn't something like this
> allow us to get a (fast) accurate count ?
> 
> SELECT COUNT(*) from table WHERE indexed_field IS NULL
> +
> SELECT COUNT(*) from table WHERE indexed_field IS NOT NULL

For certain, qualified definitions of "fast", sure.

-- 
Bill Moran
Collaborative Fusion Inc.
http://people.collaborativefusion.com/~wmoran/

wmoran@collaborativefusion.com
Phone: 412-422-3463x4023

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